1. Field of the Invention
The invention relates to apparatus employed at the intersection of two wires of opposite polarity in overhead electrically operated vehicle systems and more particularly relates to devices designed to prevent loss of power at such crossings. p 2. Description of the Prior Art:
Electric trolley buses and similar vehicles obtain power from a pair of overhead electrical conducting wires, one positive and the other negative usually at a nominal direct current voltage of 600 volts. When a pair of wires diverges from the main path, a switch is installed which changes the path of the vehicle current collectors. In this switch one of the wires of one polarity must cross the other wire which is at the opposite polarity, To prevent a short circuit, insulators are placed in one of the wires which cross. If the current collectors take the direction through the switch that does not have the insulation, no interruption to current occurs. If the direction through the switch is the one with insulators, an interruption to current occurs and this is usually associated with arcing and burning as the trolley bus loses power. In some instances a trolley bus with insufficient speed can stop under the conventional crossing device, lose power and stall. The same consequences for operation through crossings exists as at switches.
A variety of inventions addressing the difficulties encountered at these junctions are found in the prior art. For example U.S. Pat. Nos. 2,500,826, Hoover, discloses the use of short segments of standard trolley wire as replacement parts for crossovers; U.S. Pat. No. 2,727,102, Sawyer, describes a system for guiding vehicle current collectors past such crossings; and U.S. Pat. No. 2,802,072, Matthes, reveals a novel mechanical crossing assembly.
U.S. Pat. No. 2,794,867 Sawyer, details a crossing device in which power of the correct polarity is applied to the intersection coupling or pan upon the approach of the vehicle. However in this invention no provision is made for the loss of power at the insulators which connect the overhead wires to the crossing unit.
The invention disclosed herein provides a means by which power or current is always available to the vehicle at any point in the crossing. This is accomplished by the addition of an additional conducting strip along a portion of the insulators, means for powering such strips, and an improved switch for supplying power of the correct polarity to the crossing unit.